Help, After aiming for the moon on a hill climb and gravity taking over I upended my 290 and the throttle jammed wide open.After dusting myself off I NOTICED A COUPLE OF SECTIONS LATER THAT THE CRANKCASE BREATHER WAS pumping oil out and the bash plate was quite wet .Bugger.The bike ran fine and was still easy to start .There was no increase in exhaust smoke or noticeable decrease in performance.It seemed to be breathing more oil out when it was hot ,say after a section.I haven't checked the oil level yet .Any thoughts or processes of elimination I should go through ?.Any help would be appreciated.

I would say the breather tube just topped up after the upending, as with most liquids, oil spills always looks a lot worse than they are. I know cutting off the end of breather tubes to 45 degrees stops the (venturi) effect, which was a big problem on an FJ1100 yam I still own. The other cause could be too much gearbox oil ie: 500cc instead of the 450cc for a sherco!!!!!

I would say the breather tube just topped up after the upending, as with most liquids, oil spills always looks a lot worse than they are. I know cutting off the end of breather tubes to 45 degrees stops the (venturi) effect, which was a big problem on an FJ1100 yam I still own. The other cause could be too much gearbox oil ie: 500cc instead of the 450cc for a sherco!!!!!

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Thanks for that ,I have been riding for the last few weeks with oil level same@ 450 and no drama until i flipped it and it fanged it's guts out.There was more oil than youd normally find just in the breather tube.

For anyone who's interested,the fault turned out to be a worn seal on the water pump impellor shaft ,pressurizing water into gearbox,hence oil being pushed out the breather.Thank you to those who replied.

Sir Sherco,

Not sure what model you`ve got ? ,but 01 went to double seals in the pump, So there`s two seals between water and gearbox oil. If the water one goes ,it leaks out through a little indicator hole at the front of the case. Might be well worth the upgrade.?

Thanks for that, I also wondered if the gas gas set up was the same ?.